CVE-2026-55110: A malicious actor who lures an authenticated user to a malicious page could exploit a Cross-Origin Resource Sh

Q: How do I fix CVE-2026-55110?

unifi os server: upgrade to newer than 5.1.15; unifi dream machine beast firmware: upgrade to newer than 5.1.15; unifi dream machine pro firmware: upgrade to newer than 5.1.15. Exact commands for each OS are on this page.

Q: Is CVE-2026-55110 being exploited?

CVE-2026-55110 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-55110 affect?

CVE-2026-55110 affects unifi os server, unifi dream machine beast firmware, unifi dream machine pro firmware. Severity is high (CVSS 7.5). A malicious actor who lures an authenticated user to a malicious page could exploit a Cross-Origin Resource Sharing (CORS) misconfiguration found in UniFi OS to trigger actions in UniFi OS using that user's session.

Routine

HIGH 7.5UPGRADEUPGRADEUPGRADE

CVE-2026-55110 is a high-severity flaw (CVSS 7.5) affecting unifi os server, unifi dream machine beast firmware, unifi dream machine pro firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A malicious actor who lures an authenticated user to a malicious page could exploit a Cross-Origin Resource Sharing (CORS) misconfiguration found in UniFi OS to trigger actions in UniFi OS using that user's session.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 81%)
CISA exploited list	No
Weakness	CWE-942
Published	2026-07-02
Last modified	2026-07-09

Publisher (CNA): HackerOne · Vendor: ui

Last updated 2026-07-09 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-02 15:17 UTCPublished CVE record published
2026-07-09 18:33 UTCUpdated Record last modified

ui unifi os server UPGRADE

Affected: <= 5.1.15

Fixed in: newer than 5.1.15

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy unifi-os-server || rpm -q unifi-os-server || unifi-os-server --version

2. UPGRADE to newer than 5.1.15 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade unifi-os-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade unifi-os-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

ui unifi dream machine beast firmware UPGRADE

Affected: <= 5.1.15

Fixed in: newer than 5.1.15

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

ui unifi dream machine pro firmware UPGRADE

Affected: <= 5.1.15

Fixed in: newer than 5.1.15

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

ui unifi dream machine special edition firmware UPGRADE

Affected: <= 5.1.15

Fixed in: newer than 5.1.15

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

ui unifi dream machine pro max firmware UPGRADE

Affected: <= 5.1.15

Fixed in: newer than 5.1.15

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

ui enterprise fortress gateway firmware UPGRADE

Affected: <= 5.1.15

Fixed in: newer than 5.1.15

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-55110?

unifi os server: upgrade to newer than 5.1.15; unifi dream machine beast firmware: upgrade to newer than 5.1.15; unifi dream machine pro firmware: upgrade to newer than 5.1.15. Exact commands for each OS are on this page.

Is CVE-2026-55110 being exploited?

CVE-2026-55110 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-55110 affect?

CVE-2026-55110 affects unifi os server, unifi dream machine beast firmware, unifi dream machine pro firmware. Severity is high (CVSS 7.5). A malicious actor who lures an authenticated user to a malicious page could exploit a Cross-Origin Resource Sharing (CORS) misconfiguration found in UniFi OS to trigger actions in UniFi OS using that user's session.

How urgent is CVE-2026-55110?

Priority 31/100. High severity

Software pages

Ubiquiti vulnerabilities

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References

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